PIPER COMANCHE SERVICE MANrAL 2-IOa. TORQl'[ WR[~CHES. Torque wrenches should be checked dailv and calibrated bv mean!'. weights and a measured lever arm to make sure that inaccuracies are not present, Checking one torque wren against another is not sufficient and is not recommended. Somewrenchesarequitesensitiveastothewa\thev are supported during a tightening operation. Any instructions furnished by the manufacturer must be folio\\cd explicitly. When it is necessary to use a special extension or adapter wrench together with a torque \\ rench. a simple mathematical equation must be worked out to arrive at the correct torque reading. Following is the formula to be used:
(Refer to Figure 2-8a.) T ;:; Torque desired at the part. A ;:; Basic lever length from center of wrench shank to center of handle or stamped on \\ rench or listed for that model wrench. B ;:; Length of adapter extension, center of bolt to center of shank. C ;:; Scale reading needed to obtain desired torque (T). The formula: C;:; A x T EXAMPLE A bolt requires 30 foot-pounds and a 3 inch adapter (one-quarter of a foot or .25') is needed to get at it. You want to know what scale reading it will take on a one-foot lever arm wrench to obtain the 30 foot-pounds at the bolt. C ;:; I x 30 or C = 30 ;:; 24 ft.-Ibs. Remember.
the 3 inch adapter must be projecting 3 inches straight along the wrench axis. In general. avoid all complex assemblages or adapters and extensions of flex joints. T Figure 2~8a. Torque Wrench Formula IB18 REVISED: 11/1/82 HANDLl1\'G AJ'llID SERVin.